Target qubit decoupling in an echoed cross-resonance gate

ABSTRACT

Systems, computer-implemented methods, and/or computer program products that can facilitate target qubit decoupling in an echoed cross-resonance gate are provided. According to an embodiment, a computer-implemented method can comprise receiving, by a system operatively coupled to a processor, both a cross-resonance pulse and a decoupling pulse at a target qubit. The cross-resonance pulse propagates to the target qubit via a control qubit. The computer-implemented method can further comprise receiving, by the system, a state inversion pulse at the control qubit. The computer-implemented method can further comprise receiving, by the system, both a phase-inverted cross-resonance pulse and a phase-inverted decoupling pulse at the target qubit. The phase-inverted cross-resonance pulse propagates to the target qubit via the control qubit.

BACKGROUND

The subject disclosure relates to an echoed cross-resonance gate, andmore specifically, to target qubit decoupling in an echoedcross-resonance gate.

SUMMARY

The following presents a summary to provide a basic understanding of oneor more embodiments of the invention. This summary is not intended toidentify key or critical elements, or delineate any scope of theparticular embodiments or any scope of the claims. Its sole purpose isto present concepts in a simplified form as a prelude to the moredetailed description that is presented later. In one or more embodimentsdescribed herein, systems, computer-implemented methods, and/or computerprogram products that can facilitate target qubit decoupling in anechoed cross-resonance gate are described.

According to an embodiment, a computer-implemented method can comprisereceiving, by a system operatively coupled to a processor, both across-resonance pulse and a decoupling pulse at a target qubit. Thecross-resonance pulse propagates to the target qubit via a controlqubit. The computer-implemented method can further comprise receiving,by the system, a state inversion pulse at the control qubit. Thecomputer-implemented method can further comprise receiving, by thesystem, both a phase-inverted cross-resonance pulse and a phase-inverteddecoupling pulse at the target qubit. The phase-inverted cross-resonancepulse propagates to the target qubit via the control qubit.

According to another embodiment, a system can comprise a processor thatexecutes computer executable components stored in a memory. The systemcan further comprise a control qubit operatively coupled to theprocessor and that receives a cross-resonance pulse, a state inversionpulse, and a phase-inverted cross-resonance pulse. The system canfurther comprise a target qubit coupled to the control qubit and thatreceives the cross-resonance pulse, a decoupling pulse, thephase-inverted cross-resonance pulse, and a phase-inverted decouplingpulse. The cross-resonance pulse and the phase-inverted cross-resonancepulse propagate to the target qubit via the control qubit.

According to another embodiment, a computer-implemented method cancomprise applying, by a system operatively coupled to a processor, afirst pulse signal to a control qubit having a first resonant frequency.The computer-implemented method can further comprise applying, by thesystem, a second pulse signal to a target qubit coupled to the controlqubit, the target qubit having a second resonant frequency. The firstand the second pulse signals are at the second resonant frequency and inphase at the target qubit. The computer-implemented method can furthercomprise applying, by the system, a third pulse signal to the controlqubit at the first resonant frequency for creating an inverted staterelative to a current state of the control qubit. Thecomputer-implemented method can further comprise applying, by thesystem, a fourth pulse signal to the control qubit. Thecomputer-implemented method can further comprise applying, by thesystem, a fifth pulse signal to the target qubit. The fourth and thefifth pulse signals are at the second resonant frequency and are inphase at the target qubit. The fourth and fifth pulse signals include asubstantially 180 degree phase difference relative to the respectivefirst and second pulse signals.

According to another embodiment, a system can comprise a memory thatstores computer executable components and a processor that executes thecomputer executable components stored in the memory. The computerexecutable components can comprise a cross-resonance pulse componentthat applies a first pulse signal to a control qubit having a firstresonant frequency. The computer executable components can furthercomprise a decoupling pulse component that applies a second pulse signalto a target qubit coupled to the control qubit, the target qubit havinga second resonant frequency. The first and the second pulse signals areat the second resonant frequency and in phase at the target qubit. Thecomputer executable components can further comprise a state inversionpulse component that applies a third pulse signal to the control qubitat the first resonant frequency for creating an inverted state relativeto a current state of the control qubit. The computer executablecomponents can further comprise a phase-inverted cross-resonance pulsecomponent that applies a fourth pulse signal to the control qubit. Thecomputer executable components can further comprise a phase-inverteddecoupling pulse component that applies a fifth pulse signal to thetarget qubit. The fourth and the fifth pulse signals are at the secondresonant frequency and are in phase at the target qubit. The fourth andfifth pulse signals include a substantially 180 degree phase differencerelative to the respective first and second pulse signals.

According to another embodiment, a computer-implemented method cancomprise applying, by a system operatively coupled to a processor, across-resonance pulse having a first pulse period to a control qubitcoupled to a target qubit. The computer-implemented method can furthercomprise applying, by the system, a decoupling pulse having a secondpulse period to the target qubit. The cross-resonance pulse and thedecoupling pulse are at a resonant frequency of the target qubit and inphase at the target qubit. The computer-implemented method can furthercomprise applying, by the system, a phase-inverted decoupling pulsehaving a third pulse period to the target qubit at the resonantfrequency of the target qubit and including a substantially 180 degreephase difference relative to the cross-resonance pulse and thedecoupling pulse at the target qubit.

DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a block diagram of an example, non-limiting systemthat can facilitate target qubit decoupling in an echoed cross-resonancegate in accordance with one or more embodiments described herein.

FIG. 2 illustrates a diagram of an example, non-limiting pulse diagramthat can facilitate target qubit decoupling in an echoed cross-resonancegate in accordance with one or more embodiments described herein.

FIG. 3 illustrates a diagram of an example, non-limiting pulse diagramthat can facilitate target qubit decoupling in an echoed cross-resonancegate in accordance with one or more embodiments described herein.

FIG. 4 illustrates a flow diagram of an example, non-limitingcomputer-implemented method that can facilitate target qubit decouplingin an echoed cross-resonance gate in accordance with one or moreembodiments described herein.

FIG. 5 illustrates a flow diagram of an example, non-limitingcomputer-implemented method that can facilitate target qubit decouplingin an echoed cross-resonance gate in accordance with one or moreembodiments described herein.

FIG. 6 illustrates a flow diagram of an example, non-limitingcomputer-implemented method that can facilitate target qubit decouplingin an echoed cross-resonance gate in accordance with one or moreembodiments described herein.

FIG. 7 illustrates a flow diagram of an example, non-limitingcomputer-implemented method that can facilitate target qubit decouplingin an echoed cross-resonance gate in accordance with one or moreembodiments described herein.

FIG. 8 illustrates a block diagram of an example, non-limiting operatingenvironment in which one or more embodiments described herein can befacilitated.

FIG. 9 illustrates a block diagram of an example, non-limiting cloudcomputing environment in accordance with one or more embodiments of thesubject disclosure.

FIG. 10 illustrates a block diagram of example, non-limiting abstractionmodel layers in accordance with one or more embodiments of the subjectdisclosure.

DETAILED DESCRIPTION

The following detailed description is merely illustrative and is notintended to limit embodiments and/or application or uses of embodiments.Furthermore, there is no intention to be bound by any expressed orimplied information presented in the preceding Background or Summarysections, or in the Detailed Description section.

One or more embodiments are now described with reference to thedrawings, wherein like referenced numerals are used to refer to likeelements throughout. In the following description, for purposes ofexplanation, numerous specific details are set forth in order to providea more thorough understanding of the one or more embodiments. It isevident, however, in various cases, that the one or more embodiments canbe practiced without these specific details.

Cross-resonance (CR) gates are an entangling two-quantum bit (two-qubit)gate that can be used with single qubit gates to define a complete basisset for universal quantum computing. Current implementations ofcross-resonance gates suffer from coherent error sources that may becorrected in various ways, and incoherent error sources that present afundamental limit on error (the coherence limit).

For superconducting qubits, the cross-resonance gate is achieved on apair of coupled qubits by driving one (e.g., driving the control qubit)at the fundamental frequency of the other (e.g., the target qubit) usingmicrowave pulses. Undesired couplings can lead to coherent errorpreventing the error rate of the gate from reaching the coherence limit.

Some existing techniques that attempt to eliminate such undesiredcouplings that can lead to coherent error involve implementing an“echoed” cross-resonance gate. An echoed cross-resonance gate splits theoperation in two, where one half of the operation is performed, thecontrol qubit state is inverted, and the second half is performed withthe opposite phase. A problem with this technique is that it onlycancels some, but not all, sources of coherent error. For example, onecurrent technique uses pulses applied to the target qubit to correct forIX and IY rotations on the target caused by the cross-resonance pulse.The design of those pulses is intended leave only ZX rotations on thetarget to implement the cross-resonance gate (e.g., is intended to leavesome Z errors).

Given the problems described above with current implementations ofcross-resonance gates and/or echoed cross-resonance gates that sufferfrom coherent error sources, the present disclosure can be implementedto produce a solution to such problems in the form of systems,computer-implemented methods, and/or computer program products that can:apply a first pulse signal to a control qubit having a first resonantfrequency; apply a second pulse signal to a target qubit coupled to thecontrol qubit, the target qubit having a second resonant frequency,where the first and the second pulse signals are at the second resonantfrequency and in phase at the target qubit; apply a third pulse signalto the control qubit at the first resonant frequency for creating aninverted state relative to a current state of the control qubit; apply afourth pulse signal to the control qubit; and apply a fifth pulse signalto the target qubit, where the fourth and the fifth pulse signals are atthe second resonant frequency and are in phase at the target qubit, andwhere the fourth and fifth pulse signals include a substantially 180degree (180°) phase difference relative to the respective first andsecond pulse signals. By applying (e.g., simultaneously) bothcross-resonance pulses and decoupling pulses to the target qubit thatare in phase at the target qubit (e.g., applying a large IX rotation tothe target qubit to substantially cancel Z errors), the presentdisclosure can reduce the impact that undesired error sources apply totwo-qubit gates (e.g., a cross-resonance gate, an echoed cross-resonancegate, etc.) during gate operation and thereby improve computationalpower of a quantum computer comprising such gates.

FIG. 1 illustrates a block diagram of an example, non-limiting system100 that can facilitate target qubit decoupling in an echoedcross-resonance gate in accordance with one or more embodimentsdescribed herein. In some embodiments, system 100 can comprise a targetqubit decoupling system 102, which can be associated with a cloudcomputing environment. For example, target qubit decoupling system 102can be associated with cloud computing environment 950 described belowwith reference to FIG. 9 and/or one or more functional abstractionlayers described below with reference to FIG. 10 (e.g., hardware andsoftware layer 1060, virtualization layer 1070, management layer 1080,and/or workloads layer 1090).

In some embodiments, target qubit decoupling system 102 and/orcomponents thereof (e.g., cross-resonance pulse component 108,decoupling pulse component 110, state inversion pulse component 112,phase-inverted cross-resonance pulse component 114, phase-inverteddecoupling pulse component 116, etc.) can employ one or more computingresources of cloud computing environment 950 described below withreference to FIG. 9 and/or one or more functional abstraction layersdescribed below with reference to FIG. 10 to execute one or moreoperations in accordance with one or more embodiments of the subjectdisclosure described herein. For example, cloud computing environment950 and/or such one or more functional abstraction layers can compriseone or more classical computing devices (e.g., classical computer,classical processor, virtual machine, server, etc.) and/or one or morequantum computing devices (e.g., quantum computer, quantum processor,quantum circuit simulation software, superconducting circuit, etc.) thatcan be employed by target qubit decoupling system 102 and/or componentsthereof to execute one or more operations in accordance with one or moreembodiments of the subject disclosure described herein. For instance,target qubit decoupling system 102 and/or components thereof can employsuch one or more classical and/or quantum computing devices to executeone or more mathematical functions and/or equations, one or morecomputing and/or processing scripts, one or more models (e.g.,artificial intelligence (AI) models, machine learning (ML) models,etc.), one or more classical and/or quantum algorithms, and/or anotheroperation in accordance with one or more embodiments of the subjectdisclosure described herein. In another example, target qubit decouplingsystem 102 and/or components thereof can employ such one or moreclassical and/or quantum computing devices to train one or more models(e.g., artificial intelligence (AI) models, machine learning (ML)models, etc.).

It is to be understood that although this disclosure includes a detaileddescription on cloud computing, implementation of the teachings recitedherein are not limited to a cloud computing environment. Rather,embodiments of the present invention are capable of being implemented inconjunction with any other type of computing environment now known orlater developed.

Cloud computing is a model of service delivery for enabling convenient,on-demand network access to a shared pool of configurable computingresources (e.g., networks, network bandwidth, servers, processing,memory, storage, applications, virtual machines, and services) that canbe rapidly provisioned and released with minimal management effort orinteraction with a provider of the service. This cloud model may includeat least five characteristics, at least three service models, and atleast four deployment models.

Characteristics are as follows:

On-demand self-service: a cloud consumer can unilaterally provisioncomputing capabilities, such as server time and network storage, asneeded automatically without requiring human interaction with theservice's provider.

Broad network access: capabilities are available over a network andaccessed through standard mechanisms that promote use by heterogeneousthin or thick client platforms (e.g., mobile phones, laptops, and PDAs).

Resource pooling: the provider's computing resources are pooled to servemultiple consumers using a multi-tenant model, with different physicaland virtual resources dynamically assigned and reassigned according todemand. There is a sense of location independence in that the consumergenerally has no control or knowledge over the exact location of theprovided resources but may be able to specify location at a higher levelof abstraction (e.g., country, state, or datacenter).

Rapid elasticity: capabilities can be rapidly and elasticallyprovisioned, in some cases automatically, to quickly scale out andrapidly released to quickly scale in. To the consumer, the capabilitiesavailable for provisioning often appear to be unlimited and can bepurchased in any quantity at any time.

Measured service: cloud systems automatically control and optimizeresource use by leveraging a metering capability at some level ofabstraction appropriate to the type of service (e.g., storage,processing, bandwidth, and active user accounts). Resource usage can bemonitored, controlled, and reported, providing transparency for both theprovider and consumer of the utilized service.

Service Models are as follows:

Software as a Service (SaaS): the capability provided to the consumer isto use the provider's applications running on a cloud infrastructure.The applications are accessible from various client devices through athin client interface such as a web browser (e.g., web-based e-mail).The consumer does not manage or control the underlying cloudinfrastructure including network, servers, operating systems, storage,or even individual application capabilities, with the possible exceptionof limited user-specific application configuration settings.

Platform as a Service (PaaS): the capability provided to the consumer isto deploy onto the cloud infrastructure consumer-created or acquiredapplications created using programming languages and tools supported bythe provider. The consumer does not manage or control the underlyingcloud infrastructure including networks, servers, operating systems, orstorage, but has control over the deployed applications and possiblyapplication hosting environment configurations.

Infrastructure as a Service (IaaS): the capability provided to theconsumer is to provision processing, storage, networks, and otherfundamental computing resources where the consumer is able to deploy andrun arbitrary software, which can include operating systems andapplications. The consumer does not manage or control the underlyingcloud infrastructure but has control over operating systems, storage,deployed applications, and possibly limited control of select networkingcomponents (e.g., host firewalls).

Deployment Models are as follows:

Private cloud: the cloud infrastructure is operated solely for anorganization. It may be managed by the organization or a third party andmay exist on-premises or off-premises.

Community cloud: the cloud infrastructure is shared by severalorganizations and supports a specific community that has shared concerns(e.g., mission, security requirements, policy, and complianceconsiderations). It may be managed by the organizations or a third partyand may exist on-premises or off-premises.

Public cloud: the cloud infrastructure is made available to the generalpublic or a large industry group and is owned by an organization sellingcloud services.

Hybrid cloud: the cloud infrastructure is a composition of two or moreclouds (private, community, or public) that remain unique entities butare bound together by standardized or proprietary technology thatenables data and application portability (e.g., cloud bursting forload-balancing between clouds).

A cloud computing environment is service oriented with a focus onstatelessness, low coupling, modularity, and semantic interoperability.At the heart of cloud computing is an infrastructure that includes anetwork of interconnected nodes.

Continuing now with FIG. 1. According to several embodiments, targetqubit decoupling system 102 can comprise a memory 104, a processor 106,a cross-resonance pulse component 108, a decoupling pulse component 110,a state inversion pulse component 112, a phase-inverted cross-resonancepulse component 114, a phase-inverted decoupling pulse component 116,and/or a bus 118.

It should be appreciated that the embodiments of the subject disclosuredepicted in various figures disclosed herein are for illustration only,and as such, the architecture of such embodiments are not limited to thesystems, devices, and/or components depicted therein. For example, insome embodiments, system 100 and/or target qubit decoupling system 102can further comprise various computer and/or computing-based elementsdescribed herein with reference to operating environment 800 and FIG. 8.In several embodiments, such computer and/or computing-based elementscan be used in connection with implementing one or more of the systems,devices, components, and/or computer-implemented operations shown anddescribed in connection with FIG. 1 or other figures disclosed herein.

Memory 104 can store one or more computer and/or machine readable,writable, and/or executable components and/or instructions that, whenexecuted by processor 106 (e.g., a classical processor, a quantumprocessor, etc.), can facilitate performance of operations defined bythe executable component(s) and/or instruction(s). For example, memory104 can store computer and/or machine readable, writable, and/orexecutable components and/or instructions that, when executed byprocessor 106, can facilitate execution of the various functionsdescribed herein relating to target qubit decoupling system 102,cross-resonance pulse component 108, decoupling pulse component 110,state inversion pulse component 112, phase-inverted cross-resonancepulse component 114, phase-inverted decoupling pulse component 116,and/or another component associated with target qubit decoupling system102 as described herein with or without reference to the various figuresof the subject disclosure.

Memory 104 can comprise volatile memory (e.g., random access memory(RAM), static RAM (SRAM), dynamic RAM (DRAM), etc.) and/or non-volatilememory (e.g., read only memory (ROM), programmable ROM (PROM),electrically programmable ROM (EPROM), electrically erasableprogrammable ROM (EEPROM), etc.) that can employ one or more memoryarchitectures. Further examples of memory 104 are described below withreference to system memory 816 and FIG. 8. Such examples of memory 104can be employed to implement any embodiments of the subject disclosure.

Processor 106 can comprise one or more types of processors and/orelectronic circuitry (e.g., a classical processor, a quantum processor,etc.) that can implement one or more computer and/or machine readable,writable, and/or executable components and/or instructions that can bestored on memory 104. For example, processor 106 can perform variousoperations that can be specified by such computer and/or machinereadable, writable, and/or executable components and/or instructionsincluding, but not limited to, logic, control, input/output (I/O),arithmetic, and/or the like. In some embodiments, processor 106 cancomprise one or more central processing unit, multi-core processor,microprocessor, dual microprocessors, microcontroller, System on a Chip(SOC), array processor, vector processor, quantum processor, and/oranother type of processor. Further examples of processor 106 aredescribed below with reference to processing unit 814 and FIG. 8. Suchexamples of processor 106 can be employed to implement any embodimentsof the subject disclosure.

Target qubit decoupling system 102, memory 104, processor 106,cross-resonance pulse component 108, decoupling pulse component 110,state inversion pulse component 112, phase-inverted cross-resonancepulse component 114, phase-inverted decoupling pulse component 116,and/or another component of target qubit decoupling system 102 asdescribed herein can be communicatively, electrically, operatively,and/or optically coupled to one another via a bus 118 to performfunctions of system 100, target qubit decoupling system 102, and/or anycomponents coupled therewith. In several embodiments, bus 118 cancomprise one or more memory bus, memory controller, peripheral bus,external bus, local bus, a quantum bus, and/or another type of bus thatcan employ various bus architectures. Further examples of bus 118 aredescribed below with reference to system bus 818 and FIG. 8. Suchexamples of bus 118 can be employed to implement any embodiments of thesubject disclosure.

Target qubit decoupling system 102 can comprise any type of component,machine, device, facility, apparatus, and/or instrument that comprises aprocessor and/or can be capable of effective and/or operativecommunication with a wired and/or wireless network. All such embodimentsare envisioned. For example, target qubit decoupling system 102 cancomprise a server device, a computing device, a general-purposecomputer, a special-purpose computer, a quantum computing device (e.g.,a quantum computer), a tablet computing device, a handheld device, aserver class computing machine and/or database, a laptop computer, anotebook computer, a desktop computer, a cell phone, a smart phone, aconsumer appliance and/or instrumentation, an industrial and/orcommercial device, a digital assistant, a multimedia Internet enabledphone, a multimedia players, and/or another type of device.

Target qubit decoupling system 102 can be coupled (e.g.,communicatively, electrically, operatively, optically, etc.) to one ormore external systems, sources, and/or devices (e.g., classical and/orquantum computing devices, communication devices, etc.) via a data cable(e.g., High-Definition Multimedia Interface (HDMI), recommended standard(RS) 232, Ethernet cable, etc.). In some embodiments, target qubitdecoupling system 102 can be coupled (e.g., communicatively,electrically, operatively, optically, etc.) to one or more externalsystems, sources, and/or devices (e.g., classical and/or quantumcomputing devices, communication devices, etc.) via a network.

In some embodiments, such a network can comprise wired and wirelessnetworks, including, but not limited to, a cellular network, a wide areanetwork (WAN) (e.g., the Internet) or a local area network (LAN). Forexample, target qubit decoupling system 102 can communicate with one ormore external systems, sources, and/or devices, for instance, computingdevices (and vice versa) using virtually any desired wired or wirelesstechnology, including but not limited to: wireless fidelity (Wi-Fi),global system for mobile communications (GSM), universal mobiletelecommunications system (UMTS), worldwide interoperability formicrowave access (WiMAX), enhanced general packet radio service(enhanced GPRS), third generation partnership project (3GPP) long termevolution (LTE), third generation partnership project 2 (3GPP2) ultramobile broadband (UMB), high speed packet access (HSPA), Zigbee andother 802.XX wireless technologies and/or legacy telecommunicationtechnologies, BLUETOOTH®, Session Initiation Protocol (SIP), ZIGBEE®,RF4CE protocol, WirelessHART protocol, 6LoWPAN (IPv6 over Low powerWireless Area Networks), Z-Wave, an ANT, an ultra-wideband (UWB)standard protocol, and/or other proprietary and non-proprietarycommunication protocols. In such an example, target qubit decouplingsystem 102 can thus include hardware (e.g., a central processing unit(CPU), a transceiver, a decoder, a quantum processor, etc.), software(e.g., a set of threads, a set of processes, software in execution,quantum pulse schedule, quantum circuit, etc.) or a combination ofhardware and software that facilitates communicating information betweentarget qubit decoupling system 102 and external systems, sources, and/ordevices (e.g., computing devices, communication devices, etc.).

Target qubit decoupling system 102 can comprise one or more computerand/or machine readable, writable, and/or executable components and/orinstructions that, when executed by processor 106 (e.g., a classicalprocessor, a quantum processor, etc.), can facilitate performance ofoperations defined by such component(s) and/or instruction(s). Further,in numerous embodiments, any component associated with target qubitdecoupling system 102, as described herein with or without reference tothe various figures of the subject disclosure, can comprise one or morecomputer and/or machine readable, writable, and/or executable componentsand/or instructions that, when executed by processor 106, can facilitateperformance of operations defined by such component(s) and/orinstruction(s). For example, cross-resonance pulse component 108,decoupling pulse component 110, state inversion pulse component 112,phase-inverted cross-resonance pulse component 114, phase-inverteddecoupling pulse component 116, and/or any other components associatedwith target qubit decoupling system 102 as disclosed herein (e.g.,communicatively, electronically, operatively, and/or optically coupledwith and/or employed by target qubit decoupling system 102), cancomprise such computer and/or machine readable, writable, and/orexecutable component(s) and/or instruction(s). Consequently, accordingto numerous embodiments, target qubit decoupling system 102 and/or anycomponents associated therewith as disclosed herein, can employprocessor 106 to execute such computer and/or machine readable,writable, and/or executable component(s) and/or instruction(s) tofacilitate performance of one or more operations described herein withreference to target qubit decoupling system 102 and/or any suchcomponents associated therewith.

Target qubit decoupling system 102 can facilitate performance ofoperations executed by and/or associated with cross-resonance pulsecomponent 108, decoupling pulse component 110, state inversion pulsecomponent 112, phase-inverted cross-resonance pulse component 114,phase-inverted decoupling pulse component 116, and/or another componentassociated with target qubit decoupling system 102 as disclosed herein.For example, as described in detail below, target qubit decouplingsystem 102 can facilitate via processor 106 (e.g., a classicalprocessor, a quantum processor, etc.): receiving both a cross-resonancepulse and a decoupling pulse at a target qubit, where thecross-resonance pulse propagates to the target qubit via a controlqubit; receiving a state inversion pulse at the control qubit; and/orreceiving both a phase-inverted cross-resonance pulse and aphase-inverted decoupling pulse at the target qubit, where thephase-inverted cross-resonance pulse propagates to the target qubit viathe control qubit. In an example, target qubit decoupling system 102 canfurther facilitate via processor 106 (e.g., a classical processor, aquantum processor, etc.): receiving both the cross-resonance pulse andthe decoupling pulse simultaneously at the target qubit; and/orreceiving both the phase-inverted cross-resonance pulse and thephase-inverted decoupling pulse simultaneously at the target qubit,thereby facilitating at least one of improved error rate of a quantumgate comprising the target qubit and the control qubit, improvedfidelity of the quantum gate, or improved fidelity of a quantum devicecomprising the quantum gate. In an example, the cross-resonance pulseand the phase-inverted cross-resonance pulse comprise substantially sameamplitudes and pulse periods and/or substantially same 180 degree (180°)phase differences. In an example, the decoupling pulse and thephase-inverted decoupling pulse comprise substantially same amplitudesand pulse periods or substantially different amplitudes and pulseperiods and/or substantially same 180 degree (180°) phase differences.In an example, the cross-resonance pulse, the decoupling pulse, thephase-inverted cross-resonance pulse, and the phase-inverted decouplingpulse are at a resonant frequency of the target qubit.

In another example, as described in detail below, target qubitdecoupling system 102 can further facilitate via processor 106 (e.g., aclassical processor, a quantum processor, etc.): applying a first pulsesignal to a control qubit having a first resonant frequency; applying asecond pulse signal to a target qubit coupled to the control qubit, thetarget qubit having a second resonant frequency, where the first and thesecond pulse signals are at the second resonant frequency and in phaseat the target qubit; applying a third pulse signal to the control qubitat the first resonant frequency for creating an inverted state relativeto a current state of the control qubit; applying a fourth pulse signalto the control qubit; and/or applying a fifth pulse signal to the targetqubit, where the fourth and the fifth pulse signals are at the secondresonant frequency and are in phase at the target qubit, and where thefourth and fifth pulse signals include a substantially 180 degree (180°)phase difference relative to the respective first and second pulsesignals. In an example, target qubit decoupling system 102 can furtherfacilitate via processor 106 (e.g., a classical processor, a quantumprocessor, etc.): applying the first pulse signal to the control qubitand the second pulse signal to the target qubit simultaneously, wherethe first pulse signal propagates to the target qubit via the controlqubit; and/or applying the fourth pulse signal to the control qubit andthe fifth pulse signal to the target qubit simultaneously, where thefourth pulse signal propagates to the target qubit via the controlqubit. In an example, the fourth and fifth pulse signals aresubstantially the same as the first and second pulse signals. In anexample, the second and fifth pulse signals comprise substantially sameamplitudes and pulse periods. In an example, the second and fifth pulsesignals comprise substantially different amplitudes and pulse periods.

In another example, target qubit decoupling system 102 can furtherfacilitate via processor 106 (e.g., a classical processor, a quantumprocessor, etc.): applying a cross-resonance pulse having a first pulseperiod to a control qubit coupled to a target qubit; applying adecoupling pulse having a second pulse period to the target qubit, wherethe cross-resonance pulse and the decoupling pulse are at a resonantfrequency of the target qubit and in phase at the target qubit; and/orapplying a phase-inverted decoupling pulse having a third pulse periodto the target qubit at the resonant frequency of the target qubit andincluding a substantially 180 degree (180°) phase difference relative tothe cross-resonance pulse and the decoupling pulse at the target qubit.In an example, as described in detail below, target qubit decouplingsystem 102 can further facilitate via processor 106 (e.g., a classicalprocessor, a quantum processor, etc.): applying a first phase adjustmentpulse to the control qubit at a resonant frequency of the control qubit;and/or applying a second phase adjustment pulse to the target qubit atthe resonant frequency of the target qubit. In an example, as describedin detail below, target qubit decoupling system 102 can furtherfacilitate via processor 106 (e.g., a classical processor, a quantumprocessor, etc.): applying the cross-resonance pulse to the controlqubit and the decoupling pulse to the target qubit simultaneously, wherethe cross-resonance pulse propagates to the target qubit via the controlqubit; and/or applying the cross-resonance pulse to the control qubitand the phase-inverted decoupling pulse to the target qubitsimultaneously, where the cross-resonance pulse propagates to the targetqubit via the control qubit, thereby facilitating at least one ofreduced operation time of a quantum gate comprising the target qubit andthe control qubit or improved performance of a quantum device comprisingthe quantum gate. In an example, the second pulse period comprises afirst defined fraction of the first pulse period, the third pulse periodcomprises a second defined fraction of the first pulse period, and thesecond pulse period and the third pulse period together equal the firstpulse period. In an example, the decoupling pulse and the phase-inverteddecoupling pulse comprise substantially different amplitudes andsubstantially same pulse periods or the decoupling pulse and thephase-inverted decoupling pulse comprise substantially same amplitudesand substantially different pulse periods.

Cross-resonance pulse component 108 can apply a first pulse signal to acontrol qubit (not illustrated in the figures) having a first resonantfrequency. For example, cross-resonance pulse component 108 can apply afirst pulse signal comprising a cross-resonance pulse to a control qubitof a quantum gate (not illustrated in the figures) such as, forinstance, a cross-resonance gate, an echoed cross-resonance gate, and/oranother quantum gate, where such a control qubit can comprise a certainresonant frequency. In some embodiments, such a control qubit and/orquantum gate can be implemented in a quantum device (e.g., quantumcomputer, quantum processor, quantum hardware, quantum circuit,superconducting circuit, etc.) to enable one or more quantumcomputations and/or quantum data processing operations.

To facilitate applying such a pulse signal to a control qubit asdescribed above, cross-resonance pulse component 108 can employ one ormore signal devices (not illustrated in the figures) that can transmitand/or receive microwave pulse signals to and/or from a quantum devicecomprising a quantum gate and/or a control qubit (e.g., a quantum deviceand/or quantum gate defined above that comprise the control qubit). Forexample, to facilitate applying such a pulse signal to a control qubitas described above, cross-resonance pulse component 108 can employ oneor more signal devices including, but not limited to, one or morearbitrary waveform generators (AWG), radio frequency (RF) electronics,and/or local oscillators to generate and/or apply the pulse signal tothe control qubit. In some embodiments (not illustrated in the figures),such one or more signal devices can be coupled (e.g., communicatively,electrically, operatively, optically, etc.) to target qubit decouplingsystem 102 and/or one or more components thereof (e.g., memory 104,processor 106, cross-resonance pulse component 108, decoupling pulsecomponent 110, state inversion pulse component 112, phase-invertedcross-resonance pulse component 114, phase-inverted decoupling pulsecomponent 116, bus 118, etc.). In these embodiments, such one or moresignal devices can be further coupled (e.g., communicatively,electrically, operatively, optically, etc.) to a quantum device and/orquantum gate defined above that comprise the control qubit to facilitateapplying such a pulse signal to the control qubit as described above. Inthese embodiments, such a control qubit, quantum gate, quantum device,and/or signal device described above (e.g., arbitrary waveform generator(AWG), radio frequency (RF) electronics, local oscillator, etc.) canconstitute components of system 100. Decoupling pulse component 110 canapply a second pulse signal to a target qubit (not illustrated in thefigures) coupled to a control qubit, the target qubit having a secondresonant frequency, where the first and the second pulse signals are atthe second resonant frequency and in phase at the target qubit. Forexample, decoupling pulse component 110 can apply a second pulse signalcomprising a decoupling pulse to a target qubit of a quantum gate suchas, for instance, the quantum gate described above comprising a controlqubit (e.g., a cross-resonance gate, an echoed cross-resonance gate,etc.). In this example, the target qubit can be coupled to the controlqubit, the target qubit can have a certain resonant frequency (e.g., aresonant frequency that can be different than that of the controlqubit), and the first and the second pulse signals (e.g., thecross-resonance pulse and the decoupling pulse, respectively) can be atthe resonant frequency of the target qubit and in phase at the targetqubit (e.g., in phase upon arrival at the target qubit).

To facilitate applying such a pulse signal to a target qubit asdescribed above, decoupling pulse component 110 can employ one or morethe devices defined above that can transmit and/or receive microwavepulse signals to and/or from a quantum device comprising a quantum gatehaving a control qubit and a target qubit. For example, to facilitateapplying such a pulse signal to a target qubit of a quantum gate asdescribed above, decoupling pulse component 110 can employ one or moresignal devices including, but not limited to, one or more arbitrarywaveform generators (AWG), radio frequency (RF) electronics, and/orlocal oscillators to generate and/or apply the pulse signal to thetarget qubit. In some embodiments (not illustrated in the figures), suchone or more signal devices can be coupled (e.g., communicatively,electrically, operatively, optically, etc.) to target qubit decouplingsystem 102 and/or one or more components thereof (e.g., memory 104,processor 106, cross-resonance pulse component 108, decoupling pulsecomponent 110, state inversion pulse component 112, phase-invertedcross-resonance pulse component 114, phase-inverted decoupling pulsecomponent 116, bus 118, etc.). In these embodiments, such one or moresignal devices can be further coupled (e.g., communicatively,electrically, operatively, optically, etc.) to a quantum device and/orquantum gate defined above that comprise the control qubit and thetarget qubit to facilitate applying such a pulse signal to the controlqubit and/or the target qubit as described above. In these embodiments,such a control qubit, target qubit, quantum gate, quantum device, and/orsignal device described above (e.g., arbitrary waveform generator (AWG),radio frequency (RF) electronics, local oscillator, etc.) can constitutecomponents of system 100.

In some embodiments, cross-resonance pulse component 108 and decouplingpulse component 110 can employ one or more of such devices defined above(e.g., arbitrary waveform generator (AWG), radio frequency (RF)electronics, local oscillator, etc.) to simultaneously apply the firstpulse signal (e.g., the cross-resonance pulse) to a control qubit andthe second pulse signal (e.g., the decoupling pulse) to a target qubit,respectively. In these embodiments, the first pulse signal (e.g., thecross-resonance pulse) and the second pulse signal (e.g., the decouplingpulse) can arrive at the target qubit simultaneously (e.g., can bereceived by the target qubit simultaneously). In these embodiments, thefirst pulse signal (e.g., the cross-resonance pulse) that can be appliedto the control qubit by cross-resonance pulse component 108 as describedabove can propagate to the target qubit via the control qubit (e.g., dueto the coupling of the target qubit to the control qubit).

State inversion pulse component 112 can apply a third pulse signal tothe control qubit at the first resonant frequency for creating aninverted state relative to a current state of the control qubit. Forexample, state inversion pulse component 112 can apply a third pulsesignal comprising a state inversion pulse to the control qubit of thequantum gate described above. In this example, state inversion pulsecomponent 112 can apply such a pulse signal (e.g., a state inversionpulse) at the resonant frequency of the control qubit to create aninverted state (e.g., a 0 state, a 1 state, etc.) relative to a currentstate (e.g., a 0 state, a 1 state, etc.) of the control qubit.

To facilitate applying such a pulse signal to a control qubit asdescribed above, state inversion pulse component 112 can employ one ormore the devices defined above that can transmit and/or receivemicrowave pulse signals to and/or from a quantum device comprising aquantum gate having a control qubit and a target qubit. For example, tofacilitate applying such a pulse signal to a control qubit of a quantumgate as described above, state inversion pulse component 112 can employone or more signal devices including, but not limited to, one or morearbitrary waveform generators (AWG), radio frequency (RF) electronics,and/or local oscillators to generate and/or apply the pulse signal tothe control qubit.

Phase-inverted cross-resonance pulse component 114 can apply a fourthpulse signal to the control qubit. For example, phase-invertedcross-resonance pulse component 114 can apply a fourth pulse signalcomprising a phase-inverted cross-resonance pulse to the control qubitof the quantum gate described above. In this example, such a pulsesignal (e.g., a phase-inverted cross-resonance pulse) can be at theresonant frequency of the target qubit.

To facilitate applying such a pulse signal to a control qubit asdescribed above, phase-inverted cross-resonance pulse component 114 canemploy one or more the devices defined above that can transmit and/orreceive microwave pulse signals to and/or from a quantum devicecomprising a quantum gate having a control qubit and a target qubit. Forexample, to facilitate applying such a pulse signal to a control qubitof a quantum gate as described above, phase-inverted cross-resonancepulse component 114 can employ one or more signal devices including, butnot limited to, one or more arbitrary waveform generators (AWG), radiofrequency (RF) electronics, and/or local oscillators to generate and/orapply the pulse signal to the control qubit.

Phase-inverted decoupling pulse component 116 can apply a fifth pulsesignal to the target qubit, where the fourth and the fifth pulse signalsare at the second resonant frequency and are in phase at the targetqubit, and where the fourth and fifth pulse signals include asubstantially 180 degree (180°) phase difference relative to therespective first and second pulse signals. For example, phase-inverteddecoupling pulse component 116 can apply a fifth pulse signal comprisinga phase-inverted decoupling pulse to the target qubit of the quantumgate described above. In this example, the fourth and the fifth pulsesignals (e.g., the phase-inverted cross-resonance pulse and thephase-inverted decoupling pulse, respectively) can be at the resonantfrequency of the target qubit and in phase at the target qubit (e.g., inphase upon arrival at the target qubit). In this example, the fourth andthe fifth pulse signals (e.g., the phase-inverted cross-resonance pulseand the phase-inverted decoupling pulse, respectively) that can beapplied by phase-inverted cross-resonance pulse component 114 andphase-inverted decoupling pulse component 116, respectively, cancomprise a substantially 180 degree (180°) phase difference relative tothe respective first and second pulse signals (e.g., the cross-resonancepulse and the decoupling pulse, respectively) that can be applied bycross-resonance pulse component 108 and decoupling pulse component 110,respectively, as described above.

To facilitate applying such a pulse signal to a target qubit asdescribed above, phase-inverted decoupling pulse component 116 canemploy one or more the devices defined above that can transmit and/orreceive microwave pulse signals to and/or from a quantum devicecomprising a quantum gate having a control qubit and a target qubit. Forexample, to facilitate applying such a pulse signal to a target qubit ofa quantum gate as described above, phase-inverted decoupling pulsecomponent 116 can employ one or more signal devices including, but notlimited to, one or more arbitrary waveform generators (AWG), radiofrequency (RF) electronics, and/or local oscillators to generate and/orapply the pulse signal to the target qubit.

In some embodiments, phase-inverted cross-resonance pulse component 114and phase-inverted decoupling pulse component 116 can employ one or moreof such devices defined above (e.g., arbitrary waveform generator (AWG),radio frequency (RF) electronics, local oscillator, etc.) tosimultaneously apply the fourth pulse signal (e.g., the phase-invertedcross-resonance pulse) to a control qubit and the fifth pulse signal(e.g., the phase-inverted decoupling pulse) to a target qubit,respectively. In these embodiments, the fourth pulse signal (e.g., thephase-inverted cross-resonance pulse) and the fifth pulse signal (e.g.,the phase-inverted decoupling pulse) can arrive at the target qubitsimultaneously (e.g., can be received by the target qubitsimultaneously). In these embodiments, the fourth pulse signal (e.g.,the phase-inverted cross-resonance pulse) that can be applied to thecontrol qubit by phase-inverted cross-resonance pulse component 114 asdescribed above can propagate to the target qubit via the control qubit(e.g., due to the coupling of the target qubit to the control qubit).

In some embodiments, the fourth and fifth pulse signals described above(e.g., the phase-inverted cross-resonance pulse and the phase-inverteddecoupling pulse, respectively) can be substantially the same as thefirst and second pulse signals described above (e.g., thecross-resonance pulse and the decoupling pulse, respectively). In someembodiments, the second and fifth pulse signals described above (e.g.,the decoupling pulse and the phase-inverted decoupling pulse,respectively) can comprise substantially same amplitudes and pulseperiods. In some embodiments, the second and fifth pulse signalsdescribed above (e.g., the decoupling pulse and the phase-inverteddecoupling pulse, respectively) can comprise substantially differentamplitudes and pulse periods. In some embodiments, the first and fourthpulse signals described above (e.g., the cross-resonance pulse and thephase-inverted cross-resonance pulse, respectively) can comprisesubstantially same amplitudes and pulse periods, as well assubstantially same 180 degree (180°) phase differences. In someembodiments, the second and fourth pulse signals described above (e.g.,the decoupling pulse and the phase-inverted decoupling pulse,respectively) can comprise substantially same amplitudes and pulseperiods or substantially different amplitudes and pulse periods, as wellas substantially same 180 degree (180°) phase differences.

FIG. 2 illustrates a diagram of an example, non-limiting pulse diagram200 that can facilitate target qubit decoupling in an echoedcross-resonance gate in accordance with one or more embodimentsdescribed herein. Repetitive description of like elements and/orprocesses employed in respective embodiments is omitted for sake ofbrevity.

Pulse diagram 200 illustrates visual representations of the pulsesignals that can be generated and/or applied by target qubit decouplingsystem 102 to a control qubit and/or a target qubit of a quantum gate.For example, pulse signals 202, 204, 206, 208, 210 depicted in pulsediagram 200 can represent the various pulse signals that can begenerated and/or applied by target qubit decoupling system 102 to acontrol qubit and/or a target qubit of a quantum gate (e.g., across-resonance gate, an echoed cross-resonance gate, etc.) as describedabove with reference to FIG. 1.

In an example, with reference to FIGS. 1 and 2, pulse signal 202 canrepresent the first pulse signal, for instance, the cross-resonancepulse, that can be applied by cross-resonance pulse component 108 to acontrol qubit of a quantum gate comprising the control qubit and atarget qubit coupled to one another. In this example, cross-resonancepulse component 108 can apply pulse signal 202 at a resonant frequencyof the target qubit via a control channel 212 as illustrated in FIG. 2.

In another example, with reference to FIGS. 1 and 2, pulse signal 204can represent the second pulse signal, for instance, the decouplingpulse, that can be applied by decoupling pulse component 110 to thetarget qubit of the quantum gate described above comprising the controlqubit and the target qubit coupled to one another. In this example,decoupling pulse component 110 can apply pulse signal 204 at theresonant frequency of the target qubit via a target channel 214 asillustrated in FIG. 2. In this example, as described above withreference to FIG. 1, cross-resonance pulse component 108 and decouplingpulse component 110 can respectively apply pulse signals 202, 204 suchthat they arrive at the target qubit simultaneously and in phase asillustrated in FIG. 2 (denoted by the “+” symbols in FIG. 2), where thefirst pulse signal (e.g., the cross-resonance pulse) can propagate tothe target qubit via the control qubit.

In another example, with reference to FIGS. 1 and 2, pulse signal 206can represent the third pulse signal, for instance, the state inversionpulse, that can be applied by state inversion pulse component 112 to thecontrol qubit of the quantum gate comprising the control qubit and thetarget qubit coupled to one another. In this example, state inversionpulse component 112 can apply pulse signal 206 at the resonant frequencyof the control qubit via control channel 212 as illustrated in FIG. 2 tocreate an inverted state (e.g., a 0 state, a 1 state, etc.) relative toa current state (e.g., a 0 state, a 1 state, etc.) of the control qubit.

In another example, with reference to FIGS. 1 and 2, pulse signal 208can represent the fourth pulse signal, for instance, the phase-invertedcross-resonance pulse, that can be applied by phase-invertedcross-resonance pulse component 114 to the control qubit of the quantumgate comprising the control qubit and the target qubit coupled to oneanother. In this example, phase-inverted cross-resonance pulse component114 can apply pulse signal 208 at the resonant frequency of the targetqubit via control channel 212 as illustrated in FIG. 2.

In another example, with reference to FIGS. 1 and 2, pulse signal 210can represent the fifth pulse signal, for instance, the phase-inverteddecoupling pulse, that can be applied by phase-inverted decoupling pulsecomponent 116 to the target qubit of the quantum gate described abovecomprising the control qubit and the target qubit coupled to oneanother. In this example, phase-inverted decoupling pulse component 116can apply pulse signal 210 at the resonant frequency of the target qubitvia target channel 214 as illustrated in FIG. 2. In this example, asdescribed above with reference to FIG. 1, phase-inverted cross-resonancepulse component 114 and phase-inverted decoupling pulse component 116can respectively apply pulse signals 208, 210 such that they arrive atthe target qubit simultaneously and in phase as illustrated in FIG. 2(denoted by the “−” symbols in FIG. 2). In this example, the fourthpulse signal (e.g., the phase-inverted cross-resonance pulse) canpropagate to the target qubit via the control qubit and pulse signals208, 210 can comprise a substantially 180 degree (180°) phase differencerelative to pulse signals 202, 204, respectively, as denoted by the “+”symbols of pulse signals 202, 204 and the “−” symbols of pulse signals208, 210 illustrated in FIG. 2.

It should be appreciated that by respectively applying pulse signals202, 204 simultaneously at the resonant frequency of the target qubitand in phase at the target qubit and respectively applying pulse signals208, 210 simultaneously at the resonant frequency of the target qubitand in phase at the target qubit, where pulse signals 208, 210 include asubstantially 180 degree (180°) phase difference relative to pulsesignals 202, 204, target qubit decoupling system 102 can therebyfacilitate at least one of improved error rate of a quantum gatecomprising the target qubit and the control qubit, improved fidelity ofthe quantum gate, or improved fidelity of a quantum device comprisingthe quantum gate.

FIG. 3 illustrates a diagram of an example, non-limiting pulse diagram300 that can facilitate target qubit decoupling in an echoedcross-resonance gate in accordance with one or more embodimentsdescribed herein. Repetitive description of like elements and/orprocesses employed in respective embodiments is omitted for sake ofbrevity.

Pulse diagram 300 can comprise an example, non-limiting alternativeembodiment of pulse diagram 200, where pulse diagram 300 illustratesvisual representations of example, non-limiting alternative pulsesignals that can be generated and/or applied by target qubit decouplingsystem 102 to a control qubit and/or a target qubit of a quantum gate(e.g., a cross-resonance gate, an echoed cross-resonance gate, etc.).For example, pulse diagram 300 illustrates visual representations ofexample, non-limiting pulse signals that are alternative to the first,second, third, fourth, and/or fifth pulse signals (e.g., pulse signals202, 204, 206, 208, 210, respectively) described above with reference toFIGS. 1 and 2. For instance, pulse signals 302, 304, 306, 308, 310depicted in pulse diagram 300 can represent the various alternativepulse signals that can be generated and/or applied by target qubitdecoupling system 102 to a control qubit and/or a target qubit of aquantum gate as described below and above with reference to FIG. 1.

In an example, with reference to FIGS. 1, 2, and 3, pulse signal 302 canrepresent an example, non-limiting pulse signal that is an alternativeto pulse signal 202, where cross-resonance pulse component 108 can applypulse signal 302 to a control qubit of a quantum gate comprising thecontrol qubit and a target qubit coupled to one another. In thisexample, cross-resonance pulse component 108 can apply (e.g., via anarbitrary waveform generator (AWG), radio frequency (RF) electronics,local oscillator, etc.) pulse signal 302 at a resonant frequency of thetarget qubit via control channel 212 as illustrated in FIG. 3. In thisexample, pulse signal 302 can comprise a cross-resonance pulse having afirst pulse period as illustrated in FIG. 3 (e.g., a pulse period of P).

In another example, with reference to FIGS. 1, 2, and 3, pulse signal304 can represent an example, non-limiting pulse signal that is analternative to pulse signal 204, where decoupling pulse component 110can apply pulse signal 304 to a target qubit of a quantum gatecomprising a control qubit and the target qubit coupled to one another.In this example, decoupling pulse component 110 can apply (e.g., via anarbitrary waveform generator (AWG), radio frequency (RF) electronics,local oscillator, etc.) pulse signal 304 at a resonant frequency of thetarget qubit via target channel 214 as illustrated in FIG. 3. In thisexample, as illustrated in FIG. 3, pulse signal 304 can comprise adecoupling pulse having a second pulse period comprising a first definedfraction P/a of the first pulse period P of pulse signal 302, where Pand/or P/α can be defined by an entity employing target qubit decouplingsystem 102 (e.g., an entity such as, for instance, a human, a client, auser, a computing device, a software application, an agent, a machinelearning (ML) model, an artificial intelligence (AI) model, etc.). Inthis example, pulse signals 302, 304 can be in phase at the target qubit(e.g., in phase upon arrival at the target qubit as illustrated in FIG.3). For instance, cross-resonance pulse component 108 and decouplingpulse component 110 can respectively apply pulse signals 302, 304 (e.g.,the cross-resonance pulse having a pulse period P and the decouplingpulse having a pulse period P/α, respectively) such that they arrive atthe target qubit simultaneously and in phase as illustrated in FIG. 3,where pulse signal 302 (e.g., the cross-resonance pulse having a pulseperiod P) can propagate to the target qubit via the control qubit.

In another example, with reference to FIGS. 1, 2, and 3, pulse signal306 can represent an example, non-limiting pulse signal that is analternative to pulse signal 210, where phase-inverted decoupling pulsecomponent 116 can apply pulse signal 306 to a target qubit of a quantumgate comprising a control qubit and the target qubit coupled to oneanother. In this example, phase-inverted decoupling pulse component 116can apply (e.g., via an arbitrary waveform generator (AWG), radiofrequency (RF) electronics, local oscillator, etc.) pulse signal 306 ata resonant frequency of the target qubit via target channel 214. In thisexample, as illustrated in FIG. 3, pulse signal 306 can comprise aphase-inverted decoupling pulse having a third pulse period comprising asecond defined fraction P/β of the first pulse period P of pulse signal302, where P and/or P/β can be defined by an entity employing targetqubit decoupling system 102 (e.g., an entity such as, for instance, ahuman, a client, a user, a computing device, a software application, anagent, a machine learning (ML) model, an artificial intelligence (AI)model, etc.). In this example, pulse signal 306 can comprise asubstantially 180 degree (180°) phase difference relative to pulsesignals 302, 304 at the target qubit (e.g., a substantially 180 degree(180°) phase difference as denoted by the “−” symbol of pulse signal 306and the “+” symbols of pulse signals 302, 304 illustrated in FIG. 3).For instance, cross-resonance pulse component 108 and phase-inverteddecoupling pulse component 116 can respectively apply pulse signals 302,306 (e.g., the cross-resonance pulse having a pulse period P and thephase-inverted decoupling pulse having a pulse period P/β, respectively)such that they arrive at the target qubit simultaneously and with asubstantially 180 degree (180°) phase difference relative to one another(e.g., as denoted by the “−” symbol of pulse signal 306 and the “+”symbol of pulse signal 302 illustrated in FIG. 3). In these examples,pulse signal 302 (e.g., the cross-resonance pulse having a pulse periodP) can propagate to the target qubit via the control qubit.

It should be appreciated that by respectively applying pulse signals302, 304 simultaneously at the resonant frequency of the target qubitand in phase at the target qubit and respectively applying pulse signals302, 306 simultaneously at the resonant frequency of the target qubitand with a substantially 180 degree (180°) phase difference relative toone another at the target qubit, target qubit decoupling system 102 canthereby facilitate at least one of reduced operation time of a quantumgate comprising the target qubit and the control qubit or improvedperformance of a quantum device comprising the quantum gate.

In some embodiments, when combined (e.g., added together), the pulseperiod P/α of pulse signal 304 and the pulse period P/β of pulse signal306 can equal the pulse period P of pulse signal 302 as illustrated inFIG. 3 (e.g., P/α+P/β=P). In some embodiments, pulse signal 304 (e.g.,the decoupling pulse) and pulse signal 306 (e.g., the phase-inverteddecoupling pulse) can comprise substantially different amplitudes andsubstantially same pulse periods. For instance, as illustrated in FIG.3, the amplitude of pulse signal 304 can be substantially different(e.g., larger) than the amplitude of pulse signal 306 and the pulseperiod P/α of pulse signal 304 can be substantially the same as thepulse period P/β of pulse signal 306 (e.g., P/α=P/β=P/2). In someembodiments (not illustrated in the figures), pulse signal 304 (e.g.,the decoupling pulse) and pulse signal 306 (e.g., the phase-inverteddecoupling pulse) can comprise substantially same amplitudes andsubstantially different pulse periods (e.g., P/α≠P/β).

In some embodiments, target qubit decoupling system 102 can furthercomprise a phase adjustment component (not illustrated in the figures)that can apply a phase adjustment pulse comprising pulse signal 308 tothe control qubit (e.g., via control channel 212) at a resonantfrequency of the control qubit and/or a phase adjustment pulsecomprising pulse signal 310 to the target qubit (e.g., via targetchannel 214) at the resonant frequency of the target qubit asillustrated in FIG. 3. In these embodiments, such phase adjustmentpulses (e.g., pulse signals 308, 310) can be virtual or a real pulse. Ifthey are virtual phase adjustments (e.g., not real pulses), they can beimplemented through bookkeeping as an update to the angle of allsubsequent real pulses.

FIG. 4 illustrates a flow diagram of an example, non-limitingcomputer-implemented method 400 that can facilitate target qubitdecoupling in an echoed cross-resonance gate in accordance with one ormore embodiments described herein. Repetitive description of likeelements and/or processes employed in respective embodiments is omittedfor sake of brevity.

At 402, computer-implemented method 400 can comprise receiving, by asystem (e.g., via target qubit decoupling system 102, cross-resonancepulse component 108, decoupling pulse component 110, etc.) operativelycoupled to a processor (e.g., processor 106, a quantum processor, etc.),both a cross-resonance pulse (e.g., pulse signal 202 described above andillustrated in FIG. 2) and a decoupling pulse (e.g., pulse signal 204described above and illustrated in FIG. 2) at a target qubit, where thecross-resonance pulse propagates to the target qubit via a control qubit(e.g., as described above with reference to FIGS. 1 and 2).

At 404, computer-implemented method 400 can comprise receiving, by thesystem (e.g., via target qubit decoupling system 102, state inversionpulse component 112, etc.), a state inversion pulse (e.g., pulse signal206 described above and illustrated in FIG. 2) at the control qubit.

At 406, computer-implemented method 400 can comprise receiving, by thesystem (e.g., via target qubit decoupling system 102, phase-invertedcross-resonance pulse component 114, phase-inverted decoupling pulsecomponent 116, etc.), both a phase-inverted cross-resonance pulse (e.g.,pulse signal 208 described above and illustrated in FIG. 2) and aphase-inverted decoupling pulse (e.g., pulse signal 210 described aboveand illustrated in FIG. 2) at the target qubit, where the phase-invertedcross-resonance pulse propagates to the target qubit via the controlqubit (e.g., as described above with reference to FIGS. 1 and 2).

FIG. 5 illustrates a flow diagram of an example, non-limitingcomputer-implemented method 500 that can facilitate target qubitdecoupling in an echoed cross-resonance gate in accordance with one ormore embodiments described herein. Repetitive description of likeelements and/or processes employed in respective embodiments is omittedfor sake of brevity.

At 502, computer-implemented method 500 can comprise applying, by asystem (e.g., via target qubit decoupling system 102, cross-resonancepulse component 108, etc.) operatively coupled to a processor (e.g.,processor 106, a quantum processor, etc.), a first pulse signal (e.g.,pulse signal 202 described above and illustrated in FIG. 2) to a controlqubit having a first resonant frequency (e.g., as described above withreference to FIGS. 1 and 2).

At 504, computer-implemented method 500 can comprise applying, by thesystem (e.g., via target qubit decoupling system 102, decoupling pulsecomponent 110, etc.), a second pulse signal (e.g., pulse signal 204described above and illustrated in FIG. 2) to a target qubit coupled tothe control qubit, the target qubit having a second resonant frequency,where the first and the second pulse signals are at the second resonantfrequency and in phase at the target qubit (e.g., as described abovewith reference to FIGS. 1 and 2).

At 506, computer-implemented method 500 can comprise applying, by thesystem (e.g., via target qubit decoupling system 102, state inversionpulse component 112, etc.), a third pulse signal (e.g., pulse signal 206described above and illustrated in FIG. 2) to the control qubit at thefirst resonant frequency for creating an inverted state relative to acurrent state of the control qubit (e.g., as described above withreference to FIGS. 1 and 2).

At 508, computer-implemented method 500 can comprise applying, by thesystem (e.g., via target qubit decoupling system 102, phase-invertedcross-resonance pulse component 114, etc.), a fourth pulse signal (e.g.,pulse signal 208 described above and illustrated in FIG. 2) to thecontrol qubit.

At 510, computer-implemented method 500 can comprise applying, by thesystem (e.g., via target qubit decoupling system 102, phase-inverteddecoupling pulse component 116, etc.), a fifth pulse signal (e.g., pulsesignal 210 described above and illustrated in FIG. 2) to the targetqubit, where the fourth and the fifth pulse signals are at the secondresonant frequency and are in phase at the target qubit (e.g., asdescribed above with reference to FIGS. 1 and 2), and where the fourthand fifth pulse signals include a substantially 180 degree (180°) phasedifference relative to the respective first and second pulse signals(e.g., as described above with reference to FIGS. 1 and 2).

FIG. 6 illustrates a flow diagram of an example, non-limitingcomputer-implemented method 600 that can facilitate target qubitdecoupling in an echoed cross-resonance gate in accordance with one ormore embodiments described herein. Repetitive description of likeelements and/or processes employed in respective embodiments is omittedfor sake of brevity.

At 602, computer-implemented method 600 can comprise applying, by asystem (e.g., via target qubit decoupling system 102, cross-resonancepulse component 108, etc.) operatively coupled to a processor (e.g.,processor 106, a quantum processor, etc.), a cross-resonance pulsehaving a first pulse period (e.g., pulse signal 302 described above andillustrated in FIG. 3) to a control qubit coupled to a target qubit(e.g., a control qubit and a target qubit of a quantum gate such as, forinstance, a cross-resonance gate, an echoed cross-resonance gate, etc.).

At 604, computer-implemented method 600 can comprise applying, by thesystem (e.g., via target qubit decoupling system 102, decoupling pulsecomponent 110, etc.), a decoupling pulse having a second pulse period(e.g., pulse signal 304 described above and illustrated in FIG. 3) tothe target qubit, where the cross-resonance pulse and the decouplingpulse are at a resonant frequency of the target qubit and in phase atthe target qubit (e.g., in phase upon arrival at the target qubit asdescribed above and illustrated in FIG. 3).

At 606, computer-implemented method 600 can comprise applying, by thesystem (e.g., via target qubit decoupling system 102, phase-inverteddecoupling pulse component 116, etc.), a phase-inverted decoupling pulsehaving a third pulse period (e.g., pulse signal 306 described above andillustrated in FIG. 3) to the target qubit at the resonant frequency ofthe target qubit and including a substantially 180 degree (180°) phasedifference relative to the cross-resonance pulse and the decouplingpulse at the target qubit (e.g., including a substantially 180 degree(180°) phase difference as denoted by the “−” symbol of pulse signal 306and the “+” symbols of pulse signals 302, 304 illustrated in FIG. 3).

FIG. 7 illustrates a flow diagram of an example, non-limitingcomputer-implemented method 700 that can facilitate target qubitdecoupling in an echoed cross-resonance gate in accordance with one ormore embodiments described herein. Repetitive description of likeelements and/or processes employed in respective embodiments is omittedfor sake of brevity.

At 702, computer-implemented method 700 can comprise applying (e.g., viatarget qubit decoupling system 102, cross-resonance pulse component 108,etc.) a cross-resonance pulse having a first pulse period (e.g., pulsesignal 302 described above and illustrated in FIG. 3) to a control qubitcoupled to a target qubit (e.g., a control qubit and a target qubit of aquantum gate such as, for instance, a cross-resonance gate, an echoedcross-resonance gate, etc.).

At 704, computer-implemented method 700 can comprise applying (e.g., viatarget qubit decoupling system 102, decoupling pulse component 110,etc.) a decoupling pulse having a second pulse period (e.g., pulsesignal 304 described above and illustrated in FIG. 3) to the targetqubit, where the cross-resonance pulse and the decoupling pulse are at aresonant frequency of the target qubit and in phase at the target qubit(e.g., in phase upon arrival at the target qubit as described above andillustrated in FIG. 3).

At 706, computer-implemented method 700 can comprise applying (e.g., viatarget qubit decoupling system 102, phase-inverted decoupling pulsecomponent 116, etc.) a phase-inverted decoupling pulse having a thirdpulse period (e.g., pulse signal 306 described above and illustrated inFIG. 3) to the target qubit at the resonant frequency of the targetqubit and including a substantially 180 degree (180°) phase differencerelative to the cross-resonance pulse and the decoupling pulse at thetarget qubit (e.g., including a substantially 180 degree (180°) phasedifference as denoted by the “−” symbol of pulse signal 306 and the “+”symbols of pulse signals 302, 304 illustrated in FIG. 3).

In some embodiments, as described above with reference to FIG. 3, thecross-resonance pulse applied to the control qubit at 702 and thedecoupling pulse applied to the target qubit at 704 can be appliedsimultaneously by cross-resonance pulse component 108 and decouplingpulse component 110, respectively, where the cross-resonance pulse canpropagate to the target qubit via the control qubit. In theseembodiments, the cross-resonance pulse applied to the control qubit at702 and the phase-inverted decoupling pulse applied to the target qubitat 706 can be applied simultaneously by cross-resonance pulse component108 and phase-inverted decoupling pulse component 116, respectively,where the cross-resonance pulse can propagate to the target qubit viathe control qubit. In these embodiments, target qubit decoupling system102 can thereby facilitate at least one of reduced operation time of aquantum gate comprising the target qubit and the control qubit orimproved performance of a quantum device comprising the quantum gate.

At 708, computer-implemented method 700 can comprise determining (e.g.,via target qubit decoupling system 102, an entity defined above, etc.)whether operation time of a quantum gate comprising the target qubit andthe control qubit has reduced. If it is determined at 708 that operationtime of such a quantum gate comprising the target qubit and the controlqubit has not reduced, at 710, computer-implemented method 700 cancomprise modifying (e.g., via target qubit decoupling system 102, anentity defined above, etc.) the amplitude(s) of the decoupling pulseand/or the phase-inverted decoupling pulse and repeating steps 702, 704,and 706 using such modified amplitude(s).

If it is determined at 708 that operation time of such a quantum gatecomprising the target qubit and the control qubit has reduced, at 712,computer-implemented method 700 can comprise applying (e.g., via targetqubit decoupling system 102, a phase adjustment component of targetqubit decoupling system 102 (not illustrated in the figures), an entitydefined above, etc.) a first phase adjustment pulse (e.g., pulse signal308 described above and illustrated in FIG. 3) to the control qubit at aresonant frequency of the control qubit and applying (e.g., via targetqubit decoupling system 102, a phase adjustment component of targetqubit decoupling system 102 (not illustrated in the figures), an entitydefined above, etc.) a second phase adjustment pulse (e.g., pulse signal310 described above and illustrated in FIG. 3) to the target qubit atthe resonant frequency of the target qubit. At 714, computer-implementedmethod 700 can comprise ending.

Target qubit decoupling system 102 can be associated with varioustechnologies. For example, target qubit decoupling system 102 can beassociated with qubit technologies, quantum gate technologies,cross-resonance quantum gate technologies, echoed cross-resonancequantum gate technologies, quantum device technologies, microwave signalprocessing technologies, artificial intelligence technologies, machinelearning technologies, quantum computing technologies, computertechnologies, server technologies, cloud computing technologies,information technology (IT) technologies, internet-of-things (IoT)technologies, automation technologies, and/or other technologies.

Target qubit decoupling system 102 can provide technical improvements tosystems, devices, components, operational steps, and/or processing stepsassociated with the various technologies identified above. For example,by simultaneously applying both cross-resonance pulses and decouplingpulses to a target qubit that are in phase at the target qubit, targetqubit decoupling system 102 can reduce the impact that undesired errorsources (e.g., coherent error sources) apply to two-qubit gates (e.g., across-resonance gate, an echoed cross-resonance gate, etc.) during gateoperation. By reducing the affect that such undesired error sourcesapply to such two-qubit gates, target qubit decoupling system 102 canthereby improve computational power (e.g., efficiency, performance,fidelity, computational costs, etc.) of a quantum computer comprisingsuch gates. For instance, target qubit decoupling system 102 can therebyfacilitate at least one of improved error rate of a quantum gatecomprising the target qubit and the control qubit, improved fidelity ofthe quantum gate, or improved fidelity of a quantum device comprisingthe quantum gate.

Target qubit decoupling system 102 can provide technical improvements toa processing unit (e.g., processor 106) associated with a classicalcomputing device and/or a quantum computing device (e.g., a quantumprocessor, quantum hardware, superconducting circuit, etc.). Forexample, by reducing the affect that undesired error sources (e.g.,coherent error sources) apply to two-qubit gates, target qubitdecoupling system 102 can thereby improve at least one of accuracy,efficiency, performance, or fidelity of a processing unit (e.g.,processor 106, a quantum processor, etc.) comprising such gates. Suchimprovement(s) to such a processing unit can further reducecomputational costs of the processing unit.

A practical application of target qubit decoupling system 102 is that itcan be implemented in a quantum computing device (e.g., a quantumprocessor, a quantum computer, etc.) to improve processing performanceof such a device, which can facilitate fast and/or possibly universalquantum computing. Such a practical application can improve the output(e.g., computation and/or processing results) of one or more compilationjobs (e.g., quantum computing jobs) that are executed on such adevice(s).

It should be appreciated that target qubit decoupling system 102provides a new approach for reducing error rates of quantum gates inquantum devices which is driven by relatively new quantum computingtechnologies. For example, target qubit decoupling system 102 provide anew approach for reducing error rates of two-qubit quantum gates (e.g.,a cross-resonance gate, an echoed cross-resonance gate, etc.) that canbe implemented in a quantum device (e.g., quantum processor, quantumcomputer, quantum circuit, quantum hardware, etc.) to improve fidelityand/or performance of such a quantum device.

Target qubit decoupling system 102 can employ hardware or software tosolve problems that are highly technical in nature, that are notabstract and that cannot be performed as a set of mental acts by ahuman. Some of the processes described herein can be performed by one ormore specialized computers (e.g., one or more specialized processingunits, a specialized quantum computer, etc.) for carrying out definedtasks related to the various technologies identified above. Target qubitdecoupling system 102 and/or components thereof, can be employed tosolve new problems that arise through advancements in technologiesmentioned above, employment of quantum computing systems, cloudcomputing systems, computer architecture, and/or another technology.

It is to be appreciated that target qubit decoupling system 102 canutilize various combinations of electrical components, mechanicalcomponents, and circuitry that cannot be replicated in the mind of ahuman or performed by a human, as the various operations that can beexecuted by target qubit decoupling system 102 and/or components thereofas described herein are operations that are greater than the capabilityof a human mind. For instance, the amount of data processed, the speedof processing such data, or the types of data processed by target qubitdecoupling system 102 over a certain period of time can be greater,faster, or different than the amount, speed, or data type that can beprocessed by a human mind over the same period of time.

According to several embodiments, target qubit decoupling system 102 canalso be fully operational towards performing one or more other functions(e.g., fully powered on, fully executed, etc.) while also performing thevarious operations described herein. It should be appreciated that suchsimultaneous multi-operational execution is beyond the capability of ahuman mind. It should also be appreciated that target qubit decouplingsystem 102 can include information that is impossible to obtain manuallyby an entity, such as a human user. For example, the type, amount, orvariety of information included in target qubit decoupling system 102,cross-resonance pulse component 108, decoupling pulse component 110,state inversion pulse component 112, phase-inverted cross-resonancepulse component 114, and/or phase-inverted decoupling pulse component116 can be more complex than information obtained manually by a humanuser.

For simplicity of explanation, the computer-implemented methodologiesare depicted and described as a series of acts. It is to be understoodand appreciated that the subject innovation is not limited by the actsillustrated and/or by the order of acts, for example acts can occur invarious orders and/or concurrently, and with other acts not presentedand described herein. Furthermore, not all illustrated acts can beperformed to implement the computer-implemented methodologies inaccordance with the disclosed subject matter. In addition, those skilledin the art will understand and appreciate that the computer-implementedmethodologies could alternatively be represented as a series ofinterrelated states via a state diagram or events. Additionally, itshould be further appreciated that the computer-implementedmethodologies disclosed hereinafter and throughout this specificationare capable of being stored on an article of manufacture to facilitatetransporting and transferring such computer-implemented methodologies tocomputers. The term article of manufacture, as used herein, is intendedto encompass a computer program accessible from any computer-readabledevice or storage media.

In order to provide a context for the various aspects of the disclosedsubject matter, FIG. 8 as well as the following discussion are intendedto provide a general description of a suitable environment in which thevarious aspects of the disclosed subject matter can be implemented. FIG.8 illustrates a block diagram of an example, non-limiting operatingenvironment in which one or more embodiments described herein can befacilitated. Repetitive description of like elements employed in otherembodiments described herein is omitted for sake of brevity.

With reference to FIG. 8, a suitable operating environment 800 forimplementing various aspects of this disclosure can also include acomputer 812. The computer 812 can also include a processing unit 814, asystem memory 816, and a system bus 818. The system bus 818 couplessystem components including, but not limited to, the system memory 816to the processing unit 814. The processing unit 814 can be any ofvarious available processors. Dual microprocessors and othermultiprocessor architectures also can be employed as the processing unit814. The system bus 818 can be any of several types of bus structure(s)including the memory bus or memory controller, a peripheral bus orexternal bus, and/or a local bus using any variety of available busarchitectures including, but not limited to, Industrial StandardArchitecture (ISA), Micro-Channel Architecture (MSA), Extended ISA(EISA), Intelligent Drive Electronics (IDE), VESA Local Bus (VLB),Peripheral Component Interconnect (PCI), Card Bus, Universal Serial Bus(USB), Advanced Graphics Port (AGP), Firewire (IEEE 1394), and SmallComputer Systems Interface (SCSI).

The system memory 816 can also include volatile memory 820 andnonvolatile memory 822. The basic input/output system (BIOS), containingthe basic routines to transfer information between elements within thecomputer 812, such as during start-up, is stored in nonvolatile memory822. Computer 812 can also include removable/non-removable,volatile/non-volatile computer storage media. FIG. 8 illustrates, forexample, a disk storage 824. Disk storage 824 can also include, but isnot limited to, devices like a magnetic disk drive, floppy disk drive,tape drive, Jaz drive, Zip drive, LS-100 drive, flash memory card, ormemory stick. The disk storage 824 also can include storage mediaseparately or in combination with other storage media. To facilitateconnection of the disk storage 824 to the system bus 818, a removable ornon-removable interface is typically used, such as interface 826. FIG. 8also depicts software that acts as an intermediary between users and thebasic computer resources described in the suitable operating environment800. Such software can also include, for example, an operating system828. Operating system 828, which can be stored on disk storage 824, actsto control and allocate resources of the computer 812.

System applications 830 take advantage of the management of resources byoperating system 828 through program modules 832 and program data 834,e.g., stored either in system memory 816 or on disk storage 824. It isto be appreciated that this disclosure can be implemented with variousoperating systems or combinations of operating systems. A user enterscommands or information into the computer 812 through input device(s)836. Input devices 836 include, but are not limited to, a pointingdevice such as a mouse, trackball, stylus, touch pad, keyboard,microphone, joystick, game pad, satellite dish, scanner, TV tuner card,digital camera, digital video camera, web camera, and the like. Theseand other input devices connect to the processing unit 814 through thesystem bus 818 via interface port(s) 838. Interface port(s) 838 include,for example, a serial port, a parallel port, a game port, and auniversal serial bus (USB). Output device(s) 840 use some of the sametype of ports as input device(s) 836. Thus, for example, a USB port canbe used to provide input to computer 812, and to output information fromcomputer 812 to an output device 840. Output adapter 842 is provided toillustrate that there are some output devices 840 like monitors,speakers, and printers, among other output devices 840, which requirespecial adapters. The output adapters 842 include, by way ofillustration and not limitation, video and sound cards that provide ameans of connection between the output device 840 and the system bus818. It should be noted that other devices and/or systems of devicesprovide both input and output capabilities such as remote computer(s)844.

Computer 812 can operate in a networked environment using logicalconnections to one or more remote computers, such as remote computer(s)844. The remote computer(s) 844 can be a computer, a server, a router, anetwork PC, a workstation, a microprocessor based appliance, a peerdevice or other common network node and the like, and typically can alsoinclude many or all of the elements described relative to computer 812.For purposes of brevity, only a memory storage device 846 is illustratedwith remote computer(s) 844. Remote computer(s) 844 is logicallyconnected to computer 812 through a network interface 848 and thenphysically connected via communication connection 850. Network interface848 encompasses wire and/or wireless communication networks such aslocal-area networks (LAN), wide-area networks (WAN), cellular networks,etc. LAN technologies include Fiber Distributed Data Interface (FDDI),Copper Distributed Data Interface (CDDI), Ethernet, Token Ring and thelike. WAN technologies include, but are not limited to, point-to-pointlinks, circuit switching networks like Integrated Services DigitalNetworks (ISDN) and variations thereon, packet switching networks, andDigital Subscriber Lines (DSL). Communication connection(s) 850 refersto the hardware/software employed to connect the network interface 848to the system bus 818. While communication connection 850 is shown forillustrative clarity inside computer 812, it can also be external tocomputer 812. The hardware/software for connection to the networkinterface 848 can also include, for exemplary purposes only, internaland external technologies such as, modems including regular telephonegrade modems, cable modems and DSL modems, ISDN adapters, and Ethernetcards.

Referring now to FIG. 9, an illustrative cloud computing environment 950is depicted. As shown, cloud computing environment 950 includes one ormore cloud computing nodes 910 with which local computing devices usedby cloud consumers, such as, for example, personal digital assistant(PDA) or cellular telephone 954A, desktop computer 954B, laptop computer954C, and/or automobile computer system 954N may communicate. Nodes 910may communicate with one another. They may be grouped (not shown)physically or virtually, in one or more networks, such as Private,Community, Public, or Hybrid clouds as described hereinabove, or acombination thereof. This allows cloud computing environment 950 tooffer infrastructure, platforms and/or software as services for which acloud consumer does not need to maintain resources on a local computingdevice. It is understood that the types of computing devices 954A-Nshown in FIG. 9 are intended to be illustrative only and that computingnodes 910 and cloud computing environment 950 can communicate with anytype of computerized device over any type of network and/or networkaddressable connection (e.g., using a web browser).

Referring now to FIG. 10, a set of functional abstraction layersprovided by cloud computing environment 950 (FIG. 9) is shown. It shouldbe understood in advance that the components, layers, and functionsshown in FIG. 10 are intended to be illustrative only and embodiments ofthe invention are not limited thereto. As depicted, the following layersand corresponding functions are provided:

Hardware and software layer 1060 includes hardware and softwarecomponents. Examples of hardware components include: mainframes 1061;RISC (Reduced Instruction Set Computer) architecture based servers 1062;servers 1063; blade servers 1064; storage devices 1065; and networks andnetworking components 1066. In some embodiments, software componentsinclude network application server software 1067 and database software1068.

Virtualization layer 1070 provides an abstraction layer from which thefollowing examples of virtual entities may be provided: virtual servers1071; virtual storage 1072; virtual networks 1073, including virtualprivate networks; virtual applications and operating systems 1074; andvirtual clients 1075.

In one example, management layer 1080 may provide the functionsdescribed below. Resource provisioning 1081 provides dynamic procurementof computing resources and other resources that are utilized to performtasks within the cloud computing environment. Metering and Pricing 1082provide cost tracking as resources are utilized within the cloudcomputing environment, and billing or invoicing for consumption of theseresources. In one example, these resources may include applicationsoftware licenses. Security provides identity verification for cloudconsumers and tasks, as well as protection for data and other resources.User portal 1083 provides access to the cloud computing environment forconsumers and system administrators. Service level management 1084provides cloud computing resource allocation and management such thatrequired service levels are met. Service Level Agreement (SLA) planningand fulfillment 1085 provide pre-arrangement for, and procurement of,cloud computing resources for which a future requirement is anticipatedin accordance with an SLA.

Workloads layer 1090 provides examples of functionality for which thecloud computing environment may be utilized. Non-limiting examples ofworkloads and functions which may be provided from this layer include:mapping and navigation 1091; software development and lifecyclemanagement 1092; virtual classroom education delivery 1093; dataanalytics processing 1094; transaction processing 1095; and target qubitdecoupling software 1096.

The present invention may be a system, a method, an apparatus and/or acomputer program product at any possible technical detail level ofintegration. The computer program product can include a computerreadable storage medium (or media) having computer readable programinstructions thereon for causing a processor to carry out aspects of thepresent invention. The computer readable storage medium can be atangible device that can retain and store instructions for use by aninstruction execution device. The computer readable storage medium canbe, for example, but is not limited to, an electronic storage device, amagnetic storage device, an optical storage device, an electromagneticstorage device, a semiconductor storage device, or any suitablecombination of the foregoing. A non-exhaustive list of more specificexamples of the computer readable storage medium can also include thefollowing: a portable computer diskette, a hard disk, a random accessmemory (RAM), a read-only memory (ROM), an erasable programmableread-only memory (EPROM or Flash memory), a static random access memory(SRAM), a portable compact disc read-only memory (CD-ROM), a digitalversatile disk (DVD), a memory stick, a floppy disk, a mechanicallyencoded device such as punch-cards or raised structures in a groovehaving instructions recorded thereon, and any suitable combination ofthe foregoing. A computer readable storage medium, as used herein, isnot to be construed as being transitory signals per se, such as radiowaves or other freely propagating electromagnetic waves, electromagneticwaves propagating through a waveguide or other transmission media (e.g.,light pulses passing through a fiber-optic cable), or electrical signalstransmitted through a wire.

Computer readable program instructions described herein can bedownloaded to respective computing/processing devices from a computerreadable storage medium or to an external computer or external storagedevice via a network, for example, the Internet, a local area network, awide area network and/or a wireless network. The network can comprisecopper transmission cables, optical transmission fibers, wirelesstransmission, routers, firewalls, switches, gateway computers and/oredge servers. A network adapter card or network interface in eachcomputing/processing device receives computer readable programinstructions from the network and forwards the computer readable programinstructions for storage in a computer readable storage medium withinthe respective computing/processing device. Computer readable programinstructions for carrying out operations of the present invention can beassembler instructions, instruction-set-architecture (ISA) instructions,machine instructions, machine dependent instructions, microcode,firmware instructions, state-setting data, configuration data forintegrated circuitry, or either source code or object code written inany combination of one or more programming languages, including anobject oriented programming language such as Smalltalk, C++, or thelike, and procedural programming languages, such as the “C” programminglanguage or similar programming languages. The computer readable programinstructions can execute entirely on the user's computer, partly on theuser's computer, as a stand-alone software package, partly on the user'scomputer and partly on a remote computer or entirely on the remotecomputer or server. In the latter scenario, the remote computer can beconnected to the user's computer through any type of network, includinga local area network (LAN) or a wide area network (WAN), or theconnection can be made to an external computer (for example, through theInternet using an Internet Service Provider). In some embodiments,electronic circuitry including, for example, programmable logiccircuitry, field-programmable gate arrays (FPGA), or programmable logicarrays (PLA) can execute the computer readable program instructions byutilizing state information of the computer readable programinstructions to personalize the electronic circuitry, in order toperform aspects of the present invention.

Aspects of the present invention are described herein with reference toflowchart illustrations and/or block diagrams of methods, apparatus(systems), and computer program products according to embodiments of theinvention. It will be understood that each block of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented bycomputer readable program instructions. These computer readable programinstructions can be provided to a processor of a general purposecomputer, special purpose computer, or other programmable dataprocessing apparatus to produce a machine, such that the instructions,which execute via the processor of the computer or other programmabledata processing apparatus, create means for implementing thefunctions/acts specified in the flowchart and/or block diagram block orblocks. These computer readable program instructions can also be storedin a computer readable storage medium that can direct a computer, aprogrammable data processing apparatus, and/or other devices to functionin a particular manner, such that the computer readable storage mediumhaving instructions stored therein comprises an article of manufactureincluding instructions which implement aspects of the function/actspecified in the flowchart and/or block diagram block or blocks. Thecomputer readable program instructions can also be loaded onto acomputer, other programmable data processing apparatus, or other deviceto cause a series of operational acts to be performed on the computer,other programmable apparatus or other device to produce a computerimplemented process, such that the instructions which execute on thecomputer, other programmable apparatus, or other device implement thefunctions/acts specified in the flowchart and/or block diagram block orblocks.

The flowchart and block diagrams in the Figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods, and computer program products according to variousembodiments of the present invention. In this regard, each block in theflowchart or block diagrams can represent a module, segment, or portionof instructions, which comprises one or more executable instructions forimplementing the specified logical function(s). In some alternativeimplementations, the functions noted in the blocks can occur out of theorder noted in the Figures. For example, two blocks shown in successioncan, in fact, be executed substantially concurrently, or the blocks cansometimes be executed in the reverse order, depending upon thefunctionality involved. It will also be noted that each block of theblock diagrams and/or flowchart illustration, and combinations of blocksin the block diagrams and/or flowchart illustration, can be implementedby special purpose hardware-based systems that perform the specifiedfunctions or acts or carry out combinations of special purpose hardwareand computer instructions.

While the subject matter has been described above in the general contextof computer-executable instructions of a computer program product thatruns on a computer and/or computers, those skilled in the art willrecognize that this disclosure also can or can be implemented incombination with other program modules. Generally, program modulesinclude routines, programs, components, data structures, etc. thatperform particular tasks and/or implement particular abstract datatypes. Moreover, those skilled in the art will appreciate that theinventive computer-implemented methods can be practiced with othercomputer system configurations, including single-processor ormultiprocessor computer systems, mini-computing devices, mainframecomputers, as well as computers, hand-held computing devices (e.g., PDA,phone), microprocessor-based or programmable consumer or industrialelectronics, and the like. The illustrated aspects can also be practicedin distributed computing environments in which tasks are performed byremote processing devices that are linked through a communicationsnetwork. However, some, if not all aspects of this disclosure can bepracticed on stand-alone computers. In a distributed computingenvironment, program modules can be located in both local and remotememory storage devices. For example, in one or more embodiments,computer executable components can be executed from memory that caninclude or be comprised of one or more distributed memory units. As usedherein, the term “memory” and “memory unit” are interchangeable.Further, one or more embodiments described herein can execute code ofthe computer executable components in a distributed manner, e.g.,multiple processors combining or working cooperatively to execute codefrom one or more distributed memory units. As used herein, the term“memory” can encompass a single memory or memory unit at one location ormultiple memories or memory units at one or more locations.

As used in this application, the terms “component,” “system,”“platform,” “interface,” and the like, can refer to and/or can include acomputer-related entity or an entity related to an operational machinewith one or more specific functionalities. The entities disclosed hereincan be either hardware, a combination of hardware and software,software, or software in execution. For example, a component can be, butis not limited to being, a process running on a processor, a processor,an object, an executable, a thread of execution, a program, and/or acomputer. By way of illustration, both an application running on aserver and the server can be a component. One or more components canreside within a process and/or thread of execution and a component canbe localized on one computer and/or distributed between two or morecomputers. In another example, respective components can execute fromvarious computer readable media having various data structures storedthereon. The components can communicate via local and/or remoteprocesses such as in accordance with a signal having one or more datapackets (e.g., data from one component interacting with anothercomponent in a local system, distributed system, and/or across a networksuch as the Internet with other systems via the signal). As anotherexample, a component can be an apparatus with specific functionalityprovided by mechanical parts operated by electric or electroniccircuitry, which is operated by a software or firmware applicationexecuted by a processor. In such a case, the processor can be internalor external to the apparatus and can execute at least a part of thesoftware or firmware application. As yet another example, a componentcan be an apparatus that provides specific functionality throughelectronic components without mechanical parts, wherein the electroniccomponents can include a processor or other means to execute software orfirmware that confers at least in part the functionality of theelectronic components. In an aspect, a component can emulate anelectronic component via a virtual machine, e.g., within a cloudcomputing system.

In addition, the term “or” is intended to mean an inclusive “or” ratherthan an exclusive “or.” That is, unless specified otherwise, or clearfrom context, “X employs A or B” is intended to mean any of the naturalinclusive permutations. That is, if X employs A; X employs B; or Xemploys both A and B, then “X employs A or B” is satisfied under any ofthe foregoing instances. Moreover, articles “a” and “an” as used in thesubject specification and annexed drawings should generally be construedto mean “one or more” unless specified otherwise or clear from contextto be directed to a singular form. As used herein, the terms “example”and/or “exemplary” are utilized to mean serving as an example, instance,or illustration. For the avoidance of doubt, the subject matterdisclosed herein is not limited by such examples. In addition, anyaspect or design described herein as an “example” and/or “exemplary” isnot necessarily to be construed as preferred or advantageous over otheraspects or designs, nor is it meant to preclude equivalent exemplarystructures and techniques known to those of ordinary skill in the art.

As it is employed in the subject specification, the term “processor” canrefer to substantially any computing processing unit or devicecomprising, but not limited to, single-core processors;single-processors with software multithread execution capability;multi-core processors; multi-core processors with software multithreadexecution capability; multi-core processors with hardware multithreadtechnology; parallel platforms; and parallel platforms with distributedshared memory. Additionally, a processor can refer to an integratedcircuit, an application specific integrated circuit (ASIC), a digitalsignal processor (DSP), a field programmable gate array (FPGA), aprogrammable logic controller (PLC), a complex programmable logic device(CPLD), a discrete gate or transistor logic, discrete hardwarecomponents, or any combination thereof designed to perform the functionsdescribed herein. Further, processors can exploit nano-scalearchitectures such as, but not limited to, molecular and quantum-dotbased transistors, switches and gates, in order to optimize space usageor enhance performance of user equipment. A processor can also beimplemented as a combination of computing processing units. In thisdisclosure, terms such as “store,” “storage,” “data store,” datastorage,” “database,” and substantially any other information storagecomponent relevant to operation and functionality of a component areutilized to refer to “memory components,” entities embodied in a“memory,” or components comprising a memory. It is to be appreciatedthat memory and/or memory components described herein can be eithervolatile memory or nonvolatile memory, or can include both volatile andnonvolatile memory. By way of illustration, and not limitation,nonvolatile memory can include read only memory (ROM), programmable ROM(PROM), electrically programmable ROM (EPROM), electrically erasable ROM(EEPROM), flash memory, or nonvolatile random access memory (RAM) (e.g.,ferroelectric RAM (FeRAM). Volatile memory can include RAM, which canact as external cache memory, for example. By way of illustration andnot limitation, RAM is available in many forms such as synchronous RAM(SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rateSDRAM (DDR SDRAM), enhanced SDRAM (ESDRAM), Synchlink DRAM (SLDRAM),direct Rambus RAM (DRRAM), direct Rambus dynamic RAM (DRDRAM), andRambus dynamic RAM (RDRAM). Additionally, the disclosed memorycomponents of systems or computer-implemented methods herein areintended to include, without being limited to including, these and anyother suitable types of memory.

What has been described above include mere examples of systems andcomputer-implemented methods. It is, of course, not possible to describeevery conceivable combination of components or computer-implementedmethods for purposes of describing this disclosure, but one of ordinaryskill in the art can recognize that many further combinations andpermutations of this disclosure are possible. Furthermore, to the extentthat the terms “includes,” “has,” “possesses,” and the like are used inthe detailed description, claims, appendices and drawings such terms areintended to be inclusive in a manner similar to the term “comprising” as“comprising” is interpreted when employed as a transitional word in aclaim.

The descriptions of the various embodiments have been presented forpurposes of illustration, but are not intended to be exhaustive orlimited to the embodiments disclosed. Many modifications and variationswill be apparent to those of ordinary skill in the art without departingfrom the scope and spirit of the described embodiments. The terminologyused herein was chosen to best explain the principles of theembodiments, the practical application or technical improvement overtechnologies found in the marketplace, or to enable others of ordinaryskill in the art to understand the embodiments disclosed herein.

What is claimed is:
 1. A computer-implemented method of entanglingqubits, comprising: receiving, by a system operatively coupled to aprocessor, both a cross-resonance pulse and a decoupling pulse at atarget qubit, wherein the cross-resonance pulse propagates to the targetqubit via a control qubit; receiving, by the system, a state inversionpulse at the control qubit; and receiving, by the system, both aphase-inverted cross-resonance pulse and a phase-inverted decouplingpulse at the target qubit, wherein the phase-inverted cross-resonancepulse propagates to the target qubit via the control qubit.
 2. Thecomputer-implemented method of claim 1, wherein the cross-resonancepulse and the phase-inverted cross-resonance pulse comprise:substantially same amplitudes and pulse periods; and substantially same180 degree phase differences.
 3. The computer-implemented method ofclaim 1, wherein the decoupling pulse and the phase-inverted decouplingpulse comprise: substantially same amplitudes and pulse periods orsubstantially different amplitudes and pulse periods; and substantiallysame 180 degree phase differences.
 4. The computer-implemented method ofclaim 1, wherein the cross-resonance pulse, the decoupling pulse, thephase-inverted cross-resonance pulse, and the phase-inverted decouplingpulse are at a resonant frequency of the target qubit.
 5. Thecomputer-implemented method of claim 1, further comprising: receiving,by the system, both the cross-resonance pulse and the decoupling pulsesimultaneously at the target qubit; and receiving, by the system, boththe phase-inverted cross-resonance pulse and the phase-inverteddecoupling pulse simultaneously at the target qubit, therebyfacilitating at least one of improved error rate of a quantum gatecomprising the target qubit and the control qubit, improved fidelity ofthe quantum gate, or improved fidelity of a quantum device comprisingthe quantum gate.
 6. A system, comprising: a processor that executescomputer executable components stored in a memory; a control qubitoperatively coupled to the processor and that receives a cross-resonancepulse, a state inversion pulse, and a phase-inverted cross-resonancepulse; and a target qubit coupled to the control qubit and that receivesthe cross-resonance pulse, a decoupling pulse, the phase-invertedcross-resonance pulse, and a phase-inverted decoupling pulse, whereinthe cross-resonance pulse and the phase-inverted cross-resonance pulsepropagate to the target qubit via the control qubit.
 7. The system ofclaim 6, wherein the cross-resonance pulse and the phase-invertedcross-resonance pulse comprise: substantially same amplitudes and pulseperiods; and substantially same 180 degree phase differences.
 8. Thesystem of claim 6, wherein the decoupling pulse and the phase-inverteddecoupling pulse comprise: substantially same amplitudes and pulseperiods or substantially different amplitudes and pulse periods; andsubstantially same 180 degree phase differences.
 9. The system of claim6, wherein the cross-resonance pulse, the decoupling pulse, thephase-inverted cross-resonance pulse, and the phase-inverted decouplingpulse are at a resonant frequency of the target qubit.
 10. The system ofclaim 6, wherein: the target qubit receives the cross-resonance pulseand the decoupling pulse simultaneously; and the target qubit receivesthe phase-inverted cross-resonance pulse and the phase-inverteddecoupling pulse simultaneously, thereby facilitating at least one ofimproved error rate of a quantum gate comprising the target qubit andthe control qubit, improved fidelity of the quantum gate, or improvedfidelity of a quantum device comprising the quantum gate.
 11. Acomputer-implemented method of entangling qubits, comprising: applying,by a system operatively coupled to a processor, a first pulse signal toa control qubit having a first resonant frequency; applying, by thesystem, a second pulse signal to a target qubit coupled to the controlqubit, the target qubit having a second resonant frequency, wherein thefirst and the second pulse signals are at the second resonant frequencyand in phase at the target qubit; applying, by the system, a third pulsesignal to the control qubit at the first resonant frequency for creatingan inverted state relative to a current state of the control qubit;applying, by the system, a fourth pulse signal to the control qubit; andapplying, by the system, a fifth pulse signal to the target qubit,wherein the fourth and the fifth pulse signals are at the secondresonant frequency and are in phase at the target qubit, wherein thefourth and fifth pulse signals include a substantially 180 degree phasedifference relative to the respective first and second pulse signals.12. The computer-implemented method of claim 11, wherein the fourth andfifth pulse signals are substantially the same as the first and secondpulse signals.
 13. The computer-implemented method of claim 11, whereinthe second and fifth pulse signals comprise substantially sameamplitudes and pulse periods.
 14. The computer-implemented method ofclaim 11, wherein the second and fifth pulse signals comprisesubstantially different amplitudes and pulse periods.
 15. Thecomputer-implemented method of claim 11, further comprising: applying,by the system, the first pulse signal to the control qubit and thesecond pulse signal to the target qubit simultaneously, wherein thefirst pulse signal propagates to the target qubit via the control qubit;and applying, by the system, the fourth pulse signal to the controlqubit and the fifth pulse signal to the target qubit simultaneously,wherein the fourth pulse signal propagates to the target qubit via thecontrol qubit.
 16. A system, comprising: a memory that stores computerexecutable components; and a processor that executes the computerexecutable components stored in the memory, wherein the computerexecutable components comprise: a cross-resonance pulse component thatapplies a first pulse signal to a control qubit having a first resonantfrequency; a decoupling pulse component that applies a second pulsesignal to a target qubit coupled to the control qubit, the target qubithaving a second resonant frequency, wherein the first and the secondpulse signals are at the second resonant frequency and in phase at thetarget qubit; a state inversion pulse component that applies a thirdpulse signal to the control qubit at the first resonant frequency forcreating an inverted state relative to a current state of the controlqubit; a phase-inverted cross-resonance pulse component that applies afourth pulse signal to the control qubit; and a phase-inverteddecoupling pulse component that applies a fifth pulse signal to thetarget qubit, wherein the fourth and the fifth pulse signals are at thesecond resonant frequency and are in phase at the target qubit, whereinthe fourth and fifth pulse signals include a substantially 180 degreephase difference relative to the respective first and second pulsesignals.
 17. The system of claim 16, wherein the fourth and fifth pulsesignals are substantially the same as the first and second pulsesignals.
 18. The system of claim 16, wherein the second and fifth pulsesignals comprise substantially same amplitudes and pulse periods. 19.The system of claim 16, wherein the second and fifth pulse signalscomprise substantially different amplitudes and pulse periods.
 20. Thesystem of claim 16, wherein: the cross-resonance pulse component and thedecoupling pulse component respectively apply the first pulse signal andthe second pulse signal simultaneously, wherein the first pulse signalpropagates to the target qubit via the control qubit; and thephase-inverted cross-resonance pulse component and the phase-inverteddecoupling pulse component respectively apply the fourth pulse signaland the fifth pulse signal simultaneously, wherein the fourth pulsesignal propagates to the target qubit via the control qubit.
 21. Acomputer-implemented method of entangling qubits, comprising: applying,by a system operatively coupled to a processor, a cross-resonance pulsehaving a first pulse period to a control qubit coupled to a targetqubit; applying, by the system, a decoupling pulse having a second pulseperiod to the target qubit, wherein the cross-resonance pulse and thedecoupling pulse are at a resonant frequency of the target qubit and inphase at the target qubit; and applying, by the system, a phase-inverteddecoupling pulse having a third pulse period to the target qubit at theresonant frequency of the target qubit and including a substantially 180degree phase difference relative to the cross-resonance pulse and thedecoupling pulse at the target qubit.
 22. The computer-implementedmethod of claim 21, wherein: the second pulse period comprises a firstdefined fraction of the first pulse period; the third pulse periodcomprises a second defined fraction of the first pulse period; and thesecond pulse period and the third pulse period together equal the firstpulse period.
 23. The computer-implemented method of claim 21, wherein:the decoupling pulse and the phase-inverted decoupling pulse comprisesubstantially different amplitudes and substantially same pulse periods;or the decoupling pulse and the phase-inverted decoupling pulse comprisesubstantially same amplitudes and substantially different pulse periods.24. The computer-implemented method of claim 21, further comprising:applying, by the system, a first phase adjustment pulse to the controlqubit at a resonant frequency of the control qubit; and applying, by thesystem, a second phase adjustment pulse to the target qubit at theresonant frequency of the target qubit.
 25. The computer-implementedmethod of claim 21, further comprising: applying, by the system, thecross-resonance pulse to the control qubit and the decoupling pulse tothe target qubit simultaneously, wherein the cross-resonance pulsepropagates to the target qubit via the control qubit; and applying, bythe system, the cross-resonance pulse to the control qubit and thephase-inverted decoupling pulse to the target qubit simultaneously,wherein the cross-resonance pulse propagates to the target qubit via thecontrol qubit, thereby facilitating at least one of reduced operationtime of a quantum gate comprising the target qubit and the control qubitor improved performance of a quantum device comprising the quantum gate.